The invention generally relates to an improved method and apparatus for removing seeds from a roll box of ginning stands at an accelerated rate, whereby the indigenous density of seed rolls is reduced and the capacity of ginning stands is increased.
As is well understood by those familiar with the design and operation of the so-called saw-type cotton gin, a gin stand consists of a plurality of coaxially spaced saw blades mounted in mutually spaced relation on a driven shaft and having projected therebetween elongated seed roll support members, commonly referred to as ginning ribs, or, more conveniently, ribs. The teeth of the saw blades extend between the ribs and engage the fibers of seed cotton as it is fed to the gin stand. The fibers are, in turn, pulled through ginning gaps, defined by the adjacent ribs, while passage of the seeds is precluded, or at least impeded, so that the seeds are considered to be rejected. The thus rejected seeds, along with fibers not engaged by the teeth, tend to accumulate in a comingled mass to establish a seed roll which is continuously rotated in response to the action of the saw blade acting thereon. The seed roll is confined by head plates and scrolls which collectively form a cavity, commonly referred to as a roll box. Of course, the lint or fibers carried by the blades through the ribs, is doffed or removed from the teeth and delivered to subsequent stations at which additional operations are performed.
The saw blades are of a suitable diameter. Some manufacturers currently select twelve inches while others select sixteen inches. The blades are characterized by a thickness of approximately 0.036 inches to 0.038 inches. The teeth preferably are die cut with the leading edge thereof paralleling a tangent to a circle whose center is common to the center of the saw blade and whose radius is two inches less than that of a twelve inch blade and three inches less than that of a sixteen inch blade. The surface speed of the rotating blades preferably is within a range of twenty-one hundred feet per minute to twenty-eight hundred feet per minute.
Heretofore, the gin ribs were made of cast iron, mounted on a rib rail located above the saw blades, and projected below the periphery of the rotating blades. A short section of the rib, at the region thereof adjacent the teeth of the saw blades, herein referred to as the ginning point, is hardened by placing a piece of steel in a mold and chilling the metal during the casting process. A short curved section of the rib is located above and below the ginning point and normally comprises a segment of a circle having a center located above the saw blades.
Currently, it is common practice to adjust the ginning rate of a gin stand to the discharge rate for ginned seed, rather than the rate at which lint removal from the saw blades occurs. This results from the fact that the factor limiting capacity is seed discharge, simply because of the inherent increase experienced in seed roll density as the population of seeds increases within the seed roll.
When the seeds become fully ginned, that is to say, when the lint fibers are removed from the seed down to the fuzzy cover, by the action of the saw teeth acting thereon, a release of the seeds from the seed roll is initiated. This results from the agitating effect of the saw blades acting on the seed roll. However, efforts to assure that the seeds be released only when they are completely ginned have been continuing since the early days of the saw-type gin.
In order to prevent the discharge of partially ginned seeds between the saw blades, the gin rib has been so designed that its curvature below the ginning point is only slightly below the top surface of the saw blade. This, heretofore, assures that any partially ginned seed which might fall from the bottom of the seed roll will be swept back up into the seed roll by the sagging fibers of the seed roll penetrating between the saw blades.
Of course, under most conditions many of the fully ginned seeds also are swept back into the surface of the rotating seed roll. For reasons well understood by those familiar with the operation of gin stands, fully ginned seed migrate toward and tend to accumulate at the core of a seed roll, while unginned and partially ginned seed migrate toward the surface of the roll.
As is well known, the principle discharge point for ginned seed heretofore has been located at the sag in the seed roll, located in a region established adjacent the saw blades. It has been, in practice, found that the sharper the sag angle the greater the seed discharge rate. The sharpness of the sag angle is controlled, at least in part, by the contour of the ribs. Consequently, the contour of the ribs, in large measure, serve to limit seed discharge rates for seed rolls established in roll boxes of conventional gin stands.
For reasons believed to be apparent, the greater the seed density of a seed roll, the greater will be the power requirements for the gin stand, particularly the power requirements of the saw shaft. Thus, increased density results in decreased capacity at a given level of power input. Moreover, it is well known that seed roll density adversely affects the grade or quality of the lint since the lint is caused to kink, knot, etc.
It is therefore the general purpose of the instant invention to provide an improved method and apparatus for enhancing the rate of removal of fully ginned seeds from a seed roll supported by the saw blades in the roll box of a gin stand, whereby power requirements are reduced and gin capacity, as well as the quality of the resulting lint, is substantially increased.